On NetTuts.com there's a new tutorial that wants to show you a practical approach to using TDD in your development (test-driven development) through a simple project.

In this tutorial, I will present an end-to-end example of a simple application - made strictly with TDD in PHP. I will walk you through each step, one at a time, while explaining the decisions I made in order to get the task done. The example closely follows the rules of TDD: write tests, write code, refactor.

They start off by defining what TDD is (three core rules) and how the PHPUnit tool makes it easy in PHP. They use NetBeans in their examples, but it can be done similarly in any other ID (or command line). They start with some first tests - checking for word wrapping on short string and empty string handling.